Unified performance test for viscoelastic materials

ABSTRACT

The use of recycled materials can have significant economic value. With the increasing quantity of recycled material used in viscoelastic materials, especially asphalt mixture, understanding how they interact with original materials to produce a mixture that performs successfully, becomes critical. Currently, the technology to determine the effect of additives on the performance of asphalt mixture is lacking. The present invention relates to a new unified methodology for mechanical testing of asphalt mixture and other viscoelastic materials that improves the current practice in speed, convenience, and accuracy. A new improved specimen mounting method on Dynamic Shear Rheometer (DSR), a new recovery method for fine portion of asphalt mixture, and three new tests for the performance of recovered material using DSR is disclosed. The new methods provide performance grading of asphalt mixtures that is new to the industry and provide necessary tools for determining the effect of recycled materials on performance.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to the mechanical testing of viscoelasticmaterials and innovation in technologies and testing methodologies thatcan be utilized for determining the effect of recycled materials andvarious modifiers on the performance of asphalt mixtures in a unified,efficient, accurate, precise, safe, practical, and sustainable way.

Description of the Related Art

Viscoelasticity is the property of materials that exhibit both viscousand elastic characteristics when undergoing deformation. Viscoelasticmaterials (VEMs) show different behavior under different stressconditions. Some VEMs show different behavior under different moistureand/or temperature conditions. Capturing the effect of loading onresponse (i.e., deformation) of VEM is important for describing itsbehavior under various conditions (e.g. load level, temperature andmoisture). The response of a viscoelastic material to a load or stressis usually expressed in terms of deformation or strain. The loading isperformed using various loading devices.

FIG. 1 shows various Test Loading Device (TLD) used for testing VEM,including a Universal Testing Machine (UTM) in compression or tension, aDynamic Shear Rheometer (DSR) in torsion, or Dynamic mechanical Analyzer(DMA) in compression, tension and or torsion. Usually, UTM is utilizedto test large specimens, while DMA is used for medium sized specimensand DSR is used for small size specimens.

Current Standard Asphalt Binder Tests

FIG. 2 left shows a Bending Beam Rheometer (BBR) which is used fordetermining the low-temperature properties of asphalt binder usingAASHTO T 313 standard specification. This test involves molding anapproximately 10 gram bar of asphalt binder and testing it in a thirdpoint flexural device placed in the fluid bath (FIG. 2 right). A load of100 gram is applied to the middle of the bar for the duration of 240 sand the test parameters is calculated from creep stiffness at 60 s time.The BBR test is time consuming and rather tedious to perform and suffersfrom several shortcomings:

-   -   1—The BBR testing device needs constant calibration    -   2—The liquid in bath (alcohol or anti-freeze) is a health hazard    -   3—The asphalt binder bar needs to be molded and de-molded which        is time consuming    -   4—The produced bar should be tested within a narrow time limit        (4 hours)    -   5—The bar needs over 10 gram of long-term aged material which is        not easy to produce    -   6—Practically, only three tests may be accomplished in a full        day    -   7—BBR should be recalibrated every time test temperature changes

FIG. 3 shows the elements of a Dynamic Shear Rheometer (DSR) whichconsists of two plates (upper and lower plates) and a loading mechanismfor one of the plates that applies a torque that causes rotation of theplate. The sample is mounted in the gap between the parallel plates. Thecurrent asphalt binder high temperature and intermediate temperaturestandard tests are included in AASHTO M 320, which is conducted using anoscillatory Dynamic Shear Rheometer (DSR). The DSR tests utilizes arepeated sinusoidal plate movement to determine shear stress and phaseangle when material is subjected to a constant strain, which is a commonmethod in rheology. Several studies have indicated that oscillationtests cannot determine the true asphalt performance, especially whenmodifiers such as polymer and rubber is used. This is because unlike thewheels loads in the field, oscillation does not allow a pause for binderto heal itself which results in premature failure.

The mounting of asphalt binder in the gap between DSR plates isperformed according to AASHTO T 315 method which is based on manuallytrimming the outer edge of the plates by a spatula to remove the extramaterial (see FIG. 7). Manual trimming is tedious and leaves uneven edgewhich is a major cause of test variability and low precision of T 315tests. Additionally, The T 315 mounting temperatures are not sufficientto provide proper adhesion of the binder to the plates and when highstress is used during the test, it may cause partial or full detachmentof the binder from the plate. Furthermore, the AASHTO T 315 and M 320tests are not suitable for testing VEM containing fine solid particles(filler) since manual trimming and the lack of a pause in loadingprematurely damages the VEM.

Current Asphalt Aging Process

Currently, the aging of binders are conducted for two differentpurposes:

-   -   1—Short-term aging: to simulate aging in asphalt plant during        manufacturing and storage/hauling to the construction site, and    -   2—Long-term aging to simulate several years of aging in service        due to climatic conditions of the field.

FIG. 4 shows a Rolling Thin-Film Oven (RTFO) that performs simulatedshort-term aging of asphalt binder for physical and mechanical propertytesting. Asphalt binder is exposed to elevated temperatures to simulatemanufacturing and placement aging. The RTFO also provides a quantitativemeasure of the volatiles lost during the aging process. The standardRolling Thin-Film Oven test is AASHTO T 240 and ASTM D 2872: Effect ofHeat and Air on a Moving Film of Asphalt (Rolling Thin-Film Oven Test).The basic RTFO procedure takes unaged asphalt binder samples incylindrical glass bottles and places these bottles in a rotatingcarriage within an oven. The carriage rotates within the oven while the325° F. (163° C.) temperature ages the samples for 85 minutes. Samplesare then stored for use in physical and mechanical property tests or thePressure Aging Vessel (PAV). RTFO oven has had several issues thatlimits its use, especially for polymer and recycled material.

-   -   1—A major problem for asphalt binders containing polymer and        rubber is that they do not uniformly flow in the glass bottle,        thus creeping out of the bottle during the process, which        results in the binder not being aged properly    -   2—RTFO requires 35 gram in each bottle which is a lot more than        needed for the new binder tests explained in this invention. The        new and improved tests according to the invention only require        30 mg, which is 1000 times less    -   3—RTFO uses air flow that should be constantly monitored and        hard to calibrate    -   4—The fumes of the binder can be hazardous to the lungs of the        operator

FIG. 5 shows a Pressure Aging Vessel (PAV) that performs providessimulated long-term aged asphalt binder for mechanical property testing.Asphalt binder is exposed to heat and pressure to simulate in-serviceaging over a 7 to 10 year period. The standard AV procedure is found inAASHTO R 28: Accelerated Aging of Asphalt Binder Using a PressurizedAging Vessel (PAV). The basic PAV procedure takes RTFO aged asphaltbinder samples, places them in stainless steel pans and then ages themfor 20 hours in a heated vessel (usually at 100° C.) pressurized to 305psi (2.10 MPa or 20.7 atmospheres). Samples are then stored for use inmechanical property tests. PAV oven has had several issues that limitsits use, especially for polymer and rubber material.

-   -   1—In PAV steel dish the RTFO aged binder is placed in a thick        layer (about 3-mm thick) and since only surface is exposed to        air, the material is not oxidized uniformly    -   2—The pressurized air also includes nitrogen which is forced in        the binder, which does not happen in the field and the binder is        not oxidized similar to the field    -   3—PAV does not age binder to simulate the aging that occurs near        the surface of pavement, which is the location where most cracks        are initiated. It can only age the binder to simulate aging at        the bottom of the asphalt layer.    -   4—Utilizing pressurized air requires safety precautions and        regular safety inspections    -   5—PAV cannot age small quantity of viscoelastic material        Asphalt Binder Extraction and Recovery

The use of recycled materials in asphalt pavement can have significanteconomic value to the contractor and to the legislatures since it is aproper method to dispose waste. With the increasing quantity of recycledmaterials in asphalt mixtures, it becomes critical to understand how itinteracts with virgin materials to produce a mixture that will performsuccessfully in service. Currently, the extraction of the recycledasphalt binder in the laboratory is a first key step in determining theproperties. Following is a glossary of terms in relations to recycledasphalt materials:

Virgin Binder=Original liquid asphalt sold as binder without additives

RAP=Reclaimed Asphalt Pavement, Crushed pavements that are added to newpavements

RAS=Recycled Asphalt Shingles, shingles that are pulverized for use inthe new pavements

GTR=Ground Rubber Tire, Tires ground to small sizes and added to newpavements

REOB=Re-refined Engine Oil Bottom, engine oil that is processed for usein new pavements

Asphalt Additives=Polymers, rejuvenators, anti-stripping agents,warm-mix agents, Poly Phosphoric Acid (PPA), etc.

FIG. 6 shows the equipment used for extraction of binder from asphaltmixture. Currently, the effect of recycled material (RAP, RAS, engineoil etc.) on asphalt mixture is determined by extracting the binder fromthe mixture using solvent extraction and testing the extracted binder.This process uses chemical solvents (e.g. trichloroethylene,trichloroethane or methylene chloride) to dissolve the asphalt binder inthe mixture, to disintegrate the mixture, and then separate the liquidfrom the aggregate by use of a centrifuge (FIG. 6 left). The resultingliquid includes the binder and the solvent, thus solvent should beremoved from the binder using a process such as Rotavapor recoveryprocedure (FIG. 6 right). The binder extraction and recovery process hasmany shortcomings:

-   -   1—It uses a complicated and time consuming (takes 2 days)        process and it is expensive    -   2—It deals with dangerous cancer causing solutions    -   3—The process may leave some solvent in the binder that can        affect the testing results, thus may not be the true mix        representation    -   4—Contaminants may pass the filters and affect the property of        the extracted binder    -   5—The extraction/recovery process may alter the molecular        structure of the extracted binder, especially for the polymer        and rubber modified asphalt mixtures.

For the above reasons, and particularly for the hazardous nature of thesolvents, today the solvent extraction method is reluctantly used forcharacterization of the asphalt mixture. The current oscillatory bindertest methods such as the ones in AASHTO M 320 are used for testing thebinder extracted from a mixture containing recycled materials todetermine the effect of recycled material; however, oscillatory methodhas the same limitations as mentioned earlier for testing virgin binderand cannot effectively determine the effect of recycled material.

Performance Tests for Asphalt Mixtures

Due to the increased use of recycled materials and other additives inasphalt mixtures, their performance has become rather unpredictable.This is because the virgin binder does no longer determine theperformance. Therefore, testing the virgin binder does not guaranteegood performance. The interaction of recycled material (RAP, RAS, REOB)with the virgin binder depends on many factors including the source ofeach material, their chemical and physical composition, and their levelof aging (stiffening due to oxidation or loss of oil). Therefore, theonly way to predict the performance of asphalt mixtures that containsthe recycled material is to test the mixture itself.

Testing Asphalt mixture for performance is rather time consuming and isaffected by many factors. Firstly, the hot mixture of asphalt andaggregate is compacted using an asphalt compactor. Then, the compactedsamples are stored for 24 hours and then should be cut or cored to thesize using a core device and a saw and only then can be tested on aloading frame such as a Universal Testing Machine (UTM). It takes daysof work to prepare asphalt mixture specimens for mechanical testing andbecause of many factors involved, the test variability is usually ratherhigh. FIG. 8 shows a number of asphalt mixture testing equipment thatare costly to purchase, maintain and operate. This makes extensivemixture testing prohibitively expensive and impractical.

SUMMARY OF THE INVENTION

The present invention relates to a unified testing methodology forcharacterizing the behavior of Viscoelastic Materials (VEMs) thatimproves the current technology. The main invention is a new methodologyfor testing asphalt mixtures for determining the effect of recycledmaterials and modifiers. A new material called AMR and a new mountingmethod for Dynamic Shear Rheometer (DSR) are disclosed. A Pulsation DSRis introduced with three new test methods that provide indices forgrading asphalt mixture for performance.

The first embodiment of the present invention relates to a new andinnovative method of recovering the fine portion of asphalt mixturecalled Asphalt Mixture Residue (AMR).

The second embodiment of the present invention relates to a new methodof mounting the VEM on a DSR that ensures a perfect geometry and goodadhesion to the DSR plates.

The Third embodiment of the present invention relates to a new andinnovative Pulse Load Series (PLS) method for a Pulsating DSR which isnew to the field of rheometry. The test uses a small VEM sample such asbinder or AMR to determine high-temperature properties.

The fourth embodiment of the present invention relates to the testmethod for fatigue properties of the VEM using the Pulsating DSR.

The fifth embodiment of the present invention relates to thelow-temperature properties of the VEM using a DSR which is a significantimprovement over current BBR test method.

The sixth embodiment of the present invention relates to a new andimproved method of indexing the AMR. The index for AMR is develop asasphalt mixture grade comparable to the current AASHTO M320 asphaltbinder Performance Grade (PG). The Asphalt Mixture Index (AMI) may beused for determining the effect of recycled materials on performance.

The seventh embodiment of the present invention relates to a new andinnovative method of oxidative aging of the VEM to simulate in-use agingconditions.

The eight embodiment of the present invention relates to the normaltemperature properties of the VEM under one or more PLS with high stresslevels that will result in fatigue cracking of the VEM. This inventionrelates to all VEM under various loading devices in which load level ortemperature or both are increased until VEM exhibits fatigue cracking.

The ninth embodiment of the present invention is to test the VEM in dryand saturated condition to determine the effect of moisture and moisturedamage on VEM properties.

The tenth embodiment of the present invention relates to the coldtemperature properties of VEM when loaded with a constant Load. Thisembodiment relates to testing VEM using various loading devices todetermine the resistance of VEM to cracking at low temperatures. This issimilar to the fifth embodiment but applies to large VEM specimens onall TLDs.

The Eleventh embodiment of the present invention relates to the hottemperature properties of VEM using one or more series of pulse loads atlow stress levels. This is similar to the third embodiment but appliesto large VEM specimens on all TLDs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. (Prior Art) Test Loading Devices: Universal Testing Machine—UTM(Left)—Dynamic Shear Rheometer—DSR (middle)—Dynamic MechanicalAnalyzer—DMA (right) . . . 22

FIG. 2—(Prior Art) Bending Beam Rheometer—BBR Device (left) andSchematic of the BBR Test Three point Bending of Asphalt Bar in ChilledFluid (right) . . . 22

FIG. 3—(Prior Art) Elements of a Parallel Plates DSR Consisting TwoPlates that Create an adjustable Gap, Torque in one Plate, andTemperature Control for the Specimen . . . 23

FIG. 4—(Prior Art) Rolling Thin-Film Oven (RTFO) Equipment (left) andBottles (right) . . . 23

FIG. 5—(Prior Art) Pressure Aging Vessel (PAV) used for long-term agingof asphalt binder . . . 23

FIG. 6—(Prior Art) Open Centrifuge Used for Solvent Extraction ofasphalt mixture (left), Asphalt binder recovery using a Rotavaporrecovery procedure (right) . . . 24

FIG. 7—(Prior Art) DSR Asphalt Mounting Method using Manual Trimming perASASHTO 315 . . . 24

FIG. 8—(Prior Art) Various Low-Temperature Asphalt Mixture TestingEquipment . . . 24

FIG. 9—Silicon Paper with Asphalt Mixture Residue According to thePresent Invention . . . 25

FIG. 10—Roller for maximum particle size detection of AMR (left) AMRwrapped in paper passed through rolling mill with gap set to maximumparticle size plus paper thickness . . . 25

FIG. 11—Process of Mounting Asphalt Binder or AMR on DSR According tothe Invention . . . 25

FIG. 12—Melted Asphalt Binder on the DSR first plate (left), Mounted AMRwith 1.0 mm Gap (middle), and mounted asphalt Binder with 0.5-mm Gap(right) . . . 25

FIG. 13—Load and deformation for a Pulse Load Cycle Comprising PulseLoad and Zero Load 26

FIG. 14—Loading Series (LS): the response (deformation) of VEM to aSeries of loading cycles as applied to both Pulse Load Cycle (PLC) andConstant Load Cycle (CLC) . . . 26

FIG. 15—Oscillating DSR versus Pulsating DSR (DSR Sinusoidal versusPulse Load Cycle) . . . 27

FIG. 16—Normalized Stress and Strain of a Pulse Load Cycle and DC(Deformation per Cycle) in DSR showing the Pulse load of 0.1 s andZero-Load of 0.9 s (rest period that heals VEM) . . . 27

FIG. 17—A single Pulse Load Cycle for Four Different VEM tested in a DSRusing the same Shear Stress and Temperature but Showing DifferentResponse after Pulse is released . . . 27

FIG. 18—DC versus Cycles for a Pulse Load Series on DSR with SixtyCycles of 1 second . . . 28

FIG. 19—DSR Pulse Load Series for High-Temperature Test at threeTemperatures . . . 28

FIG. 20—DSR Pulse Load Series (PLS) for Five Temperatures in a FatigueTest . . . 28

FIG. 21—DSR Test for Low-Temperature Binder Showing Accumulated Strainfor Constant Load Series at three temperatures . . . 29

FIG. 22—Low-Temperature Test on DSR with Constant Loading Series ofsixty Cycles . . . 29

FIG. 23—Asphalt Mixture Index High-Temperature (AMI-high) for Mixturewith PG64-22 binder & different Quantity of RAP and RAS . . . 30

FIG. 24—Asphalt Mixture Index Low-Temperature (AMI-low) for Mixture withPG64-22 Binder and different RAP and RAS Quantities . . . 30

FIG. 25—AMI-fatigue for mixtures with PG64-22 binder and RAP and RAS . .. 31

FIG. 26—Ultra-Thin Layer of Asphalt Binder Mounted on Anodized MetalButtons for aging . . . 31

FIG. 27—Spreading Emulsions over a glass disk (Left and middle) andRecovered Asphalt Emulsions mounted on the glass or metal discs as apart of the present invention (Right) . . . 31

DETAILED DESCRIPTION OF THE INVENTION

The use of recycled materials in construction can have significanteconomic value and environmental benefits. With the increasing quantityof recycled material used in viscoelastic materials, especially asphaltbinder and mixture, understanding how they interact with originalmaterials to produce a mixture that performs successfully becomescritical. Currently, the technology to determine the effect of additiveson the performance of asphalt mixture is lacking. The present inventionrelates to a new unified methodology for mechanical testing of asphaltmixture and other viscoelastic materials that improves the currentpractice in cost, speed, convenience, lab safety, and accuracy. A newrecovery method for fine portion of asphalt mixture and a new improvedspecimen mounting method on Dynamic Shear Rheometer (DSR) are disclosedthat are essential to the grading of asphalt mixture. Subsequently,three new tests for the performance of recovered asphalt mixture using aPulsating DSR is disclosed. The new methods provide performance gradingof asphalt mixtures that is new to the industry and provide necessarytools for determining the effect of recycled materials on performance.Additionally, a new method for oxidative aging of asphalt binder and newasphalt mixture tests for fatigue, moisture damage, hot and coldcondition based on the same methodology are disclosed.

New Asphalt Mixture Residue (AMR) Recovery Method According to the FirstEmbodiment

Asphalt Mixture Residue (AMR) is the fine portion of asphalt mixturehaving particles with a predetermined maximum diameter. The new andimproved method of determining the effect of recycled material onasphalt performance in the present invention is by physically separatingAMR from asphalt mixture without the use of chemical solvents which havecaused numerous problems during the binder extraction/recovery process,some of which was described in the prior art. The physical separation ofasphalt fine particles from the aggregate particles may be performed byvarious means.

FIG. 9 shows one method of recovering AMR from asphalt mixture which isby heating the mixture on a non-stick surface (e.g., surface coated withsilicon or Teflon) and then manually or mechanically mixing the heatedmixture. When the mixture is removed from the surface, a trace of fineparticles remain, sticking to the surface. Subsequently, the surface iscooled to room temperature and shaken and or lightly rubbed so thatremaining larger than predetermined diameter particles (asphalt coatedparticles or Ground Tire Rubber-GTR) are removed from the surface. Thefine portion of asphalt mixture which is left on the non-stick surfaceis called Asphalt Mixture Residue (AMR). The AMR may be collected fromthe surface using a blade or spatula and stored in a cool place so thatit is not oxidized before testing. The AMR contains material less than apredetermined size. The maximum particle diameter depends on theapplication. For example, for testing on DSR 8-mm parallel plateconfiguration with 1.0 mm gap, the maximum AMR particle size needs to be⅓ of the gap (about 0.33 mm) so that it does not interfere with thetest. For other applications where least specime dimention is 3.0 mm,the AMR may contain particles less than 1.0 mm in size and for otherapplications the maximum size may differ. The non-stick surface shapemay differ and mixing method and heating method may be conducted usingvarious means.

FIG. 10 left shows a roller device that may be used to verify that AMRdoes not contain particles larger than a predetermined maximum sizesince these particles interfere with testing; for example, in a parallelplate DSR with 1.0-mm gap where the maximum particle size should notexceed 0.33-mm, or even preferably 0.25-mm. Different processes may beutilized to ensure that AMR does not contain particles larger than themaximum particle size. In one method, the AMR may be sandwiched betweentwo non-stick surfaces and passed through a gap between two rollers setto the predetermined maximum particle size plus the thickness of thenon-stick surfaces (see FIG. 10 right). Asphalt material larger than thepredetermined particle size will be crushed under the roller andpulverized. The pulverized material is the indication of largerparticles which may be removed from the AMR if it does not contaminatethe rest of AMR or the AMR may be rejected.

The AMR recovered using the disclosed method includes the effects ofrecycled material (RAP, RAS, Rubber, REOB), filler, polymer, fiber,anti-stripping agents, PPA, and other additives as well as the asphaltaging (stiffening of asphalt due to oxidation during production andafter construction). The AMR is subsequently tested, according to thepresent invention, to determine the effect of recycled material on themixture properties, change in grade, and therefore predict performanceonce placed in the field.

New and Innovative DSR Specimen Mounting Method According to the SecondEmbodiment

Proper mounting of the VEM on a DSR parallel plate is important for theconduct of the test. In the normal and low temperature DSR tests wherehigh stress levels are utilized, lack of sufficient adhesion between theVEM specimen and the plates can cause partial or complete detachment ofthe VEM from one surface that will affect the test results. As discussedin prior art, current asphalt mounting method in AASHTO T 315 disturbsthe sample at the edge of plates and is a major factor in test resultvariation (FIG. 7), the mounting temperatures of T 315 are notsufficient to provide proper adhesion to the plates, and manual trimmingis not suitable for VEM with fine particles. Therefore, a new andimproved VEM mounting method is disclosed in this invention for theuniform and symmetrical placement of the VEM and for achieving goodadhesion between VEM and the two plates. This method is suitable formounting virgin and aged asphalt binders and AMR, as well as any VEMthat is temperature sensitive. FIG. 11 shows the proper mounting of VEMin a gap of a parallel plate DSR that should leave a reasonable bulge.

FIG. 11 (1) shows the first step of mounting, according to the presentinvention, where sufficient VEM is weighed at room temperature such thatit fills the gap and leaves a proper bulge as shown in the right side ofFIG. 11. This weight is calculated from the Gap and Bulge volume and theVEM density. For example, for 8-mm parallel plate diameter (d) and 0.5mm gap, the sufficient weight of asphalt binder aged with RTFO/PAV isbetween 30 to 32 mg. For the 8-mm plate diameter and 1.0 mm gap DSRgeometry used for the VEM with fine particles or Asphalt Mixture Residue(AMR), 80 to 100 mg of is sufficient to fill the gap and leave areasonable bulge. For 25-mm diameter plate and 1.0 mm Gap, about 510 mgof binder is sufficient.

FIG. 11 (2) shows the second step of mounting according to the presentinvention where VEM is placed on the entire first plate of a DSR and thetemperature is set to a first temperature and kept for a firstpredetermined duration to completely melt VEM. This temperature isselected such that VEM creates a symmetrical dome-shaped appearance(also see FIG. 12 right). The surface tensions always keep VEM on thesurface and it will not flow over the edge. Typically, for asphaltbinder and AMR, this temperature is about 30 to 50° C. higher thanbinder's high-temperature Performance Grade (PG); however, thetemperature and the duration may vary for different VEM types.

FIG. 11 (3) shows the third step of mounting the VEM, where thetemperature is set to a second temperature suitable for mounting of thesecond plate on the asphalt dome. The second temperature is selectedsuch that asphalt does not flow out of the gap once the plates reachpredetermined gap. Typically, this temperature is 10 to 20° C. less thanthe first temperature for asphalt binders. Once the DSR reaches thesecond temperature, the second plate is moved towards the first plate toreach a predetermined gap. In the fourth step, the mounted specimen iskept under the second temperature for a second predetermined duration toachieve proper adhesion to the second plate. The second temperature andduration depends on several factors including the PG grade of the binderor AMR and whether the binder is modified using polymer, rubber, PPA,etc. The mounted specimen looks like FIG. 12 right for asphalt binderand FIG. 12 left for AMR.

Glossary of Pulse Loading Series Method for VEM According to the PresentInvention

New tests for the viscoelastic materials (VEM) utilize two types ofloading (Constant or Pulse Loading) which may be applied using any TLD(UTM or DSR) and in any direction (compression, tension, or torsion). Asegment of loading that is repeated is called a Load Cycle. For example,a 60 second constant load test may consist of 60 identical one secondloading segments. Following is a glossary of terms for VEM loadingmethodology which is specific to the present invention. Examples andlimits for each test parameter is given in the next sections when theLoading Series and new tests are disclosed for DSR and UTM.

Pulse Load Cycles (PLC) comprises a load pulse with a predeterminedMaximum Stress and a predetermined duration followed by a longerzero-load (pause) period with no load. FIG. 13 top shows two pulse loadcycles. Load pulse duration in this invention is typically less than 1.0second for asphalts and is applied as quickly as possible. Zero-loaddoes not include the constant load that is sometimes applied for keepingthe sample in place (Seating Load).

Constant Load Cycle (CLC) is a special case when the VEM is subjected toa constant maximum stress for the entire cycle duration. In this method,contrary to the Pulse Load Cycle, there is no zero-load (pause)duration.

Deformation per Cycle (DC) is permanent deformation at the end of eachPLC or CLC (see FIG. 13 bottom graph). DC is the deformation from thebeginning to the end of one cycle and is not accumulated from previouscycles. For CLC, DC is same as max. deformation.

DC Ratio (DCR) is the ratio of DC to maximum deformation. For CLC, whereDC is the same as maximum deformation, DCR is 1.0 but for Pulse LoadCycle, it is a number less than 1.0.

Loading Series (LS) is defined as a series of repeated identical LoadCycles (see FIG. 14) that when applied to a VEM, the DC is initiallysubstantially reduced for each cycle (Initial Region) until DC becomesstable and does not significantly change (Stable Region), and finally DCreaches zero and subsequently start to increase (Unstable Region).

Pulse Load Series (PLS) is when loading cycle is Pulse Load Cycle (PLC)

Constant Load Series (CLS) is when loading cycle is Constant Load Cycle(CLC).

Deformation Acceleration (DA): The rate of change of DC, which is thechange in DC at the end of any Load Cycle, compared with DC of theprevious cycles (see FIG. 14). DA is a large negative number in InitialRegion (DC substantially reduces with each cycle); and a small negativenumber approaching zero in Stable Region (DC does not changesignificantly); and a positive number in Unstable Region when DC startsto increase with each cycle.

Region I, Initial Region (IR) is the test region where the DC reducessignificantly with each load cycle (see FIG. 14) and DA is a highnegative value but reducing with each cycle.

Region II, Stable Region (SR) is the test region where the DC becomesstable (does not change significantly). DC is still reducing but at asignificantly lower rate and DA is a low negative value approachingzero.

Region III, Unstable Region (UR) is the test region where DC starts toincrease and DA becomes a positive value.

Stable Deformation per Cycle (SDC) is the permanent Deformation perCycle (DC) after test enters Stable Region (SR) and before test reachesUnstable Region. Unstable DC (UDC) is the Deformation per Cycle (DC)when test enters Unstable Region (UR).

Total Deformation (TD) is the sum of all Deformations per cycles (DC)for all cycles.

Span is the initial DC (for the first cycle) minus the SDC, which is thechange in DC between the first cycle and the cycle when DC reachesStable Region.

New Pulsating Dynamic Shear Rheometer (DSR)

To improve the existing VEM test methods conducted on a Dynamic ShearRheometer (DSR), a new and innovative method called the Pulse LoadSeries (PLS) method is disclosed here which follows the methodologydisclosed under section “Glossary of Pulse Loading Series Method forVEM” above. In the PLS method, the sample is subjected to successivePulse Load Cycles on a DSR (Pulsating DSR). Pulsating DSR is a type ofloading that would provide improved results over the currently utilizedoscillatory (sinusoidal) and shear rate tests for testing the VEM on DSR(Oscillation DSR).

FIG. 15 shows the difference between a prior art Oscillation DSR and aPulsating DSR according to the invention. It shows an oscillation cycleon DSR where the upper plate starts from position A and a torque makesit to oscillate between points B and C in a sinusoidal shape; however,in a Pulse load Cycle, the load (torque) is quickly applied that movesthe upper plate from initial position A towards position B andsubsequently the load is released (zero-load) and the upper plate movesback towards position A. Therefore, in oscillation, plate movesbi-directional and forces the material to move with it but in Pulsemethod the applied load always moves the material in one direction andthen releases it to move back on itself. The Pulse Load Cycle (PLC)resembles the passing of a single wheel load over a point in asphaltpavement and for this reason, it has shown to provide much closerresults to the field than oscillation. The PLC is also the preferredmethod for testing VEM containing fine particles (e.g. AMR) becauseunlike oscillation, it gives material a rest duration to heal itself andthus loading does not prematurely damages the material.

FIG. 16 shows an example of the Pulse Load Cycle (PLC) for DSR in whichthe VEM is subjected to a one second pulse load cycle comprising amaximum shear stress for duration of 0.1 s followed by a zero stresslevel (pause) for 0.9 s (stress shown by the dotted line). The solidline in FIG. 16 shows the response (i.e. strain) during the loadingcycle. The strain increases to a maximum level and then when the stressis removed after 0.1 s, the VEM rebounds to some degree during the 0.9second zero-load period. The permanent deformation at the end of 1.0 scycle (DC) and DC Ratio (DCR) are the cycle parameters.

FIG. 17 shows examples of Load Pulse Cycles for four different VEMs(VEM1-4) tested at the same stress level. It shows that differentmaterials rebound differently, VEM1 has the Maximum strain of 5.15% andDC of 5% with DCR of about 0.97 while VEM4 has maximum strain of 5% andDC of 0.1% and DCR of 0.02. The DC and DCR for the other two VEM are inbetween. This shows that some VEM can heal more than others after loadis released.

FIG. 18 shows the DC versus time for Pulse Load Series (PLS) method thatincludes a series of identical successive Pulse Load Cycles (PLC) withstress level high enough to bring the test to the Stable Region (SR).The parameter of the PLS is Total Deformation (TD), Span and Deformationper cycle at the Stable Region (SDC) which is the cycle at which DC doesnot change substantially with additional cycles. FIG. 18 is an exampleof the Pulse Load Series (PLS) for Pulsating DSR with parallel plateconfiguration comprising a first and second plate. In this example, 8-mmdiameter plate was used for asphalt binder with 0.5 mm gap and the testwas conducted at 25° C. with 500 kPa pulse stress level. FIG. 18 showsthat sixty pulse load cycles (each of 1.0 s duration) was applied to aVEM specimen and the permanent deformation per cycle (DC) has decreasedfrom initial 350 (for the first cycle) to about 100 microstrain (for the60th cycle) and has reached Stable Region (DC is not significantlychanging with cycles). The Stable Deformation per Cycle (SDC) for thisload series is then 100 microstrain and the Span is 350−100=250microstrain. Total Deformation (TD) is sum of all DCs for all 60 cycles.

The Pulsating DSR methodology may be utilized for any VEM including butnot limited to powder, soil, oil, polymers, rubber, asphalt binder,asphalt mixture, Asphalt Mixture Residue, plastics, gum, melts, andlatex having any shape or size and using any DSR configuration anattachment. The test may be conducted at any temperature within therange of DSR capabilities. This includes very high temperatures(typically above 100° C.), high temperature (typically between 40 and100° C.), normal temperature (between 0 and 40° C.), and or lowtemperature (typically less than 0° C.). The Pulsating DSR is ideal fortesting AMR at high temperature to determine asphalt rutting potentialand at normal temperature to determine its fatigue resistance and tograde asphalt mixture.

Improved High-Temperature Test Using PLS Method According to the ThirdEmbodiment

The present invention discloses a new and innovative methodology fortesting VEM at high-temperature using a Pulsating Dynamic ShearRheometer (DSR). The invention comprises mounting the VEM specimen on aDSR, setting the temperature to a predetermined hot temperature andallowing sufficient time for the uniform spread of temperature, andapplying a Pulse Load Series (PLS) of a first predetermined stress untilthe test reaches the Stable Region (SR) and does not reach UnstableRegion (UR).

FIG. 19 shows an example of high temperature test using PLS method onDSR for a PG70-22 binder at three temperatures where the SDC at 70° C.is around 29%. In this example, the pulse stress level was 5.0 kPa forduration of 0.1 s and Stable Region was reached after 20 cycles of onesecond each. Optionally, the stress may be increased to a second andthird predetermined levels and the PLS be repeated at each level stresslevel to provide an SDC corresponding to each stress level.

In another embodiment of the present invention, the test is conducted ona DSR with parallel plates of 8-mm diameter and the gap depth of 0.5-mmfor asphalt binder or 1.0-mm for AMR or VEM with fine particles. Foroxidized asphalt binder using RTFO procedure, the binder is mounted onDSR, the temperature is set to high-temperature PG (Performance Grade)of the binder and PLS with maximum stress of typically between 1 and 30kPa is applied for 60 cycles. The maximum stress level varies with theDSR geometry and VEM type, however, it should be high enough to bringVEM to the Stable Region (SR) but not excessively high to cause the testto enter the Unstable Region. In the high-temperature test, the PLSshould always end in the Stable Region (SR) where DA is a low negativenumber close to zero.

In another embodiment of the present invention, the Pulsating DSR withparallel plates of 25-mm diameter is used for a very-high temperaturetest. The gap between parallel plates is 1.0-mm and the temperature isset to a very high temperature between 100 and 200° C. that melts VEM.Once the VEM is mounted on a DSR, the temperature is set to apredetermined temperature and sufficient time is allowed for uniformthermal condition, a PLS is applied on the VEM with 0.1 s load and 0.9 szero-load period. In this embodiment, since VEM is in the fluid state,the test is always past initial and stable region and will be in theUnstable Region (UR) and DC is higher than the maximum strain. The teststress level is selected based on the type of DSR geometry and VEM typesuch that DC is not so excessive to force the VEM outside the mounting.The test parameters are Span, Total Deformation (TD) and StableDeformation per Cycle (SDC) and the end of each Load Series. Onevariation of this test is for virgin asphalt binder tested at the mixingor compaction temperature.

The high-temperature DSR test may be conducted on a variety of VEMmaterials including but not limited to oil, recycled engine oil (REOB),rubber, rubber improved materials, gum, polymer, latex, plastic,original asphalt binder, oxidized asphalt binder, asphalt emulsions,recovered AMR or asphalt binder from asphalt mixture. The temperaturemay be any high temperature typically above 30 and mostly between 40 and100° C.

Improved Fatigue Test for Pulsating DSR According to the FourthEmbodiment

The present invention discloses a new and innovative VEM fatigue testmethod using a Pulsating Dynamic Shear Rheometer (DSR). The inventioncomprises mounting the VEM specimen on a DSR, setting the temperature toa first predetermined normal-temperature between 0 and 40° C. andapplying a Pulse Load Series (PLS) until test reaches the Stable Region(SR) and does not reach Unstable Region (UR) in the first PLS. The testparameters are TD, Span and the Stable Deformation per Cycle (SDC) atthe end of each PLS. The stress magnitude is selected based on DSRgeometry and VEM type such that it can bring the material to the Stableregion and induce measurable amount of SDC.

FIG. 20 shows an example of fatigue test output for an asphalt binder.The test is conducted on a DSR with parallel plates of 8-mm diameter andthe gap depth of 0.5-mm. The lowest curve in FIG. 20 discloses the firstPulse Load Series (PLS) consists of 60 cycles of one seconds each (500kPa stress and 0.1 s load pulse duration), applied to VEM after it hasuniformly reached 21° C. The Deformation Acceleration (DA) at the end offirst PLS is still negative (DC is reducing), which is an indicationthat the material is still in the Stable Region and has not reachedUnstable region. The SDC at this temperature is about 40 millistrains.The temperature is subsequently raised by one degree to 22° C. and thesame PLS is repeated (second line from bottom) and the DA is stillnegative. The PLS is repeated at 23° C. and 24° C. and the DA isapproaching zero at 24° C. Repeating the PLS at 25° C. causes the DA tobecome negative (DC starts to increase) which is the indicative thatmaterial has entered Unstable Region (UR). At this PLS, the VEM hasinitiated fatigue cracking. The cycle when VEM enters Unstable Region(marked as UDC in FIG. 20) is the cycle that fatigue cracking isinitiated. The fatigue index of VEM, according to the present invention,is the SDC in the PLS before the material reaches Unstable Region and DAis zero. Fatigue index indicates how much the material may be strainedin a Pulse Load Series before it starts to exhibit cracking. Thetemperature for the PLS before the material initiates cracking (SDC) iscalled Intermediate Temperature (IT) of the material. Therefore, thematerial in FIG. 20 has Fatigue Index (SDC) of about 80 millistrain atthe Intermediate Temperature of 24° C.

In one embodiment of the present invention, the test is conducted on aDSR with parallel plates of 8-mm diameter and the gap depth 1.0-mm forAMR or VEM with fine particles. For oxidized asphalt binder using RTFOplus PAV procedure, the VEM is mounted on DSR, the temperature is set tonormal temperature and PLS with maximum stress of typically between 400and 800 kPa is applied. The stress should be such that a series of 60cycles is adequate to bring the test to the Stable Region (SR). Thistest may be conducted on a variety of VEM materials including but notlimited to oil, recycled engine oil (REOB), rubber, rubber improvedmaterials, gum, polymer, latex, plastic, original asphalt binder,oxidized asphalt binder, asphalt emulsions residue, recovered AMR. Theinitial temperature and maximum stress for PLS is determined such thatVEM reaches the Stable Region (SR) but does not reach the UnstableRegion in the first load series. However, the VEM should reach theUnstable Region (UR) by applying four to eight PLS at differenttemperatures in order to reach intermediate temperature.

New and Improved Low-Temperature Test for DSR According to the FifthEmbodiment

The present invention includes a new and innovative Low-Temperature testmethod for VEM using a Dynamic Shear Rheometer (DSR). As mentionedbefore, the current standard for low-temperature test is conducted usingBBR which has significant limitations. However, the present inventionhas removed several of the limitations of the BBR by utilizing a DSRwhile providing comparable asphalt Performance Grade (PG).

The invention comprises mounting the VEM specimen on the DSR, reducingthe temperature to a first predetermined Low Temperature typically equalto or less than 0° C. and waiting for uniform temperature reached, andsubsequently applying a constant predetermined shear stress (CLS) suchthat test reaches the Stable Region (SR) and does not reach UnstableRegion (UR). The specimen temperature may be reduced to a second orthird or fourth predetermined test temperature and the test repeated.The test parameters are Span, Total Deformation (TD) and StableDeformation per Cycle (SDC) and the end of each Load Series. The teststress level is selected based on the type of DSR geometry and VEM typesuch that it can bring the VEM to SR and the SDC can be a measurableamount.

FIG. 21 shows an example of the test conducted on a DSR with parallelplates of 8-mm diameter and the gap depth of 0.5-mm utilizing 1000 kPastress for an asphalt binder that is oxidized using RTFO/PAV procedures.The y-axis (Y) is the total strain in % and x-axis is time in seconds.The test was conducted in three steps. In the first step, thetemperature is reduced to 0° C. and sufficient time is allowed for theVEM to uniformly reach the temperature. Subsequently, a CLS (ConstantLoad Series) of 60 cycles (each one second duration) applied to bringthe test to the Stable Region. In the next step, the VEM temperature isreduced to −6° C. and the same CLS repeated. This process is repeatedafter reducing the temperature to −12° C. where TD (total strain) at theend of cycle was 2.7%.

FIG. 22 shows similar data to FIG. 21 in terms of Deformation per Cycle(DC) for Constant Load Cycle (CLC) of one second cycle time. The linefor −12° C. shows that DC was initially about 540 microstrains (ms) butreduced substantially in Initial Region and reached the Stable Region(SR) after 60 cycles (seconds). This is evidenced by negative DA whichindicates that DC is still reducing at the end of 60 s. The StableDeformation per Cycle (SDC) for this Load Series is about 30 microstrain(ms).

In one embodiment of the present invention, the test is conducted forAMR or VEM with fine particles with 8-mm plate diameter and the gapdepth of 1.0-mm. For oxidized asphalt binder using RTFO plus PAVprocedure, the VEM is mounted on DSR, the temperature is set to Lowtemperature and CLS with maximum stress of typically between 100 and1500 kPa is applied. The stress should be such that it brings the testto the Stable Region (SR) but does not reach Unstable Region. This testmay be conducted on a variety of VEM materials including but not limitedto oil, recycled engine oil (REOB), rubber, rubber improved materials,gum, polymer, latex, plastic, asphalt binder, oxidized asphalt binder,recovered AMR. The temperature may be any low temperature less thanequal 0° C., but normally the temperature can be set to a fixpredetermined temperature (e.g. −5° C.) or like BBR test, 10° C. abovethe low-temperature PG of the asphalt binder (−6, −12, −18, −24 or −30°C.).

New and Innovative Asphalt Mixture Index (AMI) According to the SixthEmbodiment

Currently, a grading for asphalt mixture does not exist. The grading ofasphalt mixture is critical for determining the effect of recycledmaterial on asphalt performance. The new and innovative Asphalt MixtureResidue (AMR), the new mounting method for DSR, and Pulsating DSRdisclosed as a part of the present invention is utilized to disclose anew grading system for the Asphalt Mixture called Asphalt Mixture Index(AMI). The AMI is determined by testing AMR utilizing high and lowtemperature and fatigue cracking tests on DSR separately orconsecutively in a series of tests with a single mounting. Therefore,new grading system comprises three components for AMI-high, AMI-low, andAMI-fatigue. In all three DSR test methods, TD, Span and Deformation perCycle at Stable Region (SDC) parameter is used for grading the mixturesimilar to the grading of asphalt binder. When only virgin binderwithout additives is used in the mixture, AMI grade will be similar tobinder PG; however, with the addition of recycled material (RAP and RAS)AMI changes.

FIG. 23 discloses an example of High-Temperature grade (AMI-high) forfour asphalt mixtures that have same binder grade (PG64-22) butdifferent quantity of RAP and RAS. The AMR was recovered from theasphalt mixture and was tested using at the High-Temperature usingPulsating DSR to determine the SDC. AMI-high is the temperature at whichSDC has a predetermined value. FIG. 23 discloses that the AMIsubstantially increases (from 68 to 84° C.) when 20% RAP is added to themixture. This is due to the stiffening of the mixture as a result ofusing RAP, which is much stiffer old pavement that are crushed and addedto new pavements. The addition of 20% RAS (Shingles) increases the AMIto 99° C.

FIG. 24 discloses the Low-Temperature Asphalt Mixture Index (AMI-low)determined using the mixture AMR and the CLS method of DSR. The AMI-lowis the temperature at which SDC is a predetermined value. FIG. 24 showsAMI-low for the same mixtures as for AMI-high. The AMI was reduced from−24.5° C. for PG 64-22 mixture to about −22° C. when 20% RAP and −18° C.when 40% RAP was used in the mixture. The increase in AMI-low is causedby the effect of recycled material which significantly reduces theasphalt durability.

FIG. 25 discloses the Mixture Fatigue Cracking Index AMI (AMI-fatigue).The AMI-fatigue is the SDC of the Pulsating DSR fatigue test atintermediate temperature. FIG. 25 shows AMI-fatigue for the samemixtures as for AMI-high. The AMI is 11.0 microstrains (ms) for mixtureswithout RAP or RAS but reduces to 6.5 ms for mixture with 20% RAP andfurther to 5 ms for mixture with 40% RAP. For mixture with 20% RAS(Shingles), the AMI further drops to 4 ms which shows that the mixturehas lost its fatigue resistance due to the use of RAP.

The three AMIs disclosed in the present invention can be quicklydetermined and the Pulsating DSR tests are easy to perform. It does notsuffer from numerous limitations and shortcomings of extracting binderfrom mixture and current standard asphalt binder tests. The AMR recoveryprocess may be performed in the laboratory, asphalt plant or at the timeof construction within a few minutes. The recovered AMR may beimmediately tested to determine the AMI and asphalt mixture performancegrade in less than 30 minutes. The cost of performing the AMI tests is afraction of the cost of performing mixture tests and is much safer. Forthis reason, the AMI tests are ideal for Quality Control of asphaltmixtures.

Ultra-Thin Film Aging of Asphalt Binders and AMRs According to theSeventh Embodiment

FIG. 26 discloses a new and innovative aging procedure in the presentinvention that resolves numerous issues with the current asphalt agingprocess using RTFO and PAV. The new and innovative method utilizes verythin layers of VEM (asphalt binder or AMR) on flat surfaces. VEM isplaced on a flat surface in an ultra-thin film thickness similar tosteps 1 and 2 of DSR mounting method by weighing and melting VEM. Thethickness is approximately 250 microns for asphalt binders (12 timesless than PAV) and typically between 200 and 600 microns for allapplications. The ultra-thin layer makes oxidation significantly easierand more homogeneous in a regular force draft oven without the need topressurize the oven. The material is then evenly mounted on the surfaceof a metal or glass disk (FIG. 26). The material is subsequentlytransferred to a forced-draft oven for aging. Typical aging times andtemperatures for asphalt binders and AMR are as follows:

-   -   1—Short-term aging of asphalt binder is performed in 60 minutes        duration at about 120° C. to simulate RTFO or between 100 to        200° C. for other applications    -   2—Long-term aging of asphalt binder (PAV) may be performed for        20 hours at 100° C.    -   3—Long-term aging of Asphalt Mixture Residue (AMR) may be        performed at 85° C. for various length of time to simulate aging        at different time.

Oxidative aging of any VEM including oil, rubber and rubber improvedmaterials, polymer and polymer modified material, gum, and paint may beconducted using this method but at proper temperature and duration.

Ultra-Thin Film Recovery and Aging of Asphalt Emulsions

FIG. 27 discloses a variation of the present invention for the residuerecovery and oxidative aging of asphalt emulsions on flat surfaces thatimproves the current process. The recovered and aged emulsions may betested with DSR for hot, normal and cold temperature properties.

The first step is the mounting of emulsions on the flat surface that isshown in the FIG. 27 left and middle where a predetermined weight ofemulsions is evenly spread over the surface to create a predeterminedlayer thickness. The weight is determined from the layer thickness andthe emulsions density (which is normally close to 1.0). For example,applying 1.2 gram of emulsions over a 2.5 in. diameter glass disk, willcreate a 0.38 mm layer. This thickness is similar to the current AASHTOPP72 Method B specification; however, this method may be applied to anyother layer thickness and VEM including heated asphalt binder and AMR.Some of the applications of the present mounting is as follows:

-   -   1—To recover the emulsions, the disc is placed in forced-draft        oven at 60° C. for 6 hours.    -   2—Alternatively, the emulsions may be recovered in a heated        vacuum chamber with the temperature of 60° C. and absolute        pressure of 5-mm HG for shorter time period, or any other        combination of temperature, vacuum level, and duration.    -   3—For long-term aging, the recovered binder resulting from 1 or        2 above may be aged in the forced-draft oven for 16 hours at        125° C., or any other combination of temperature and time        depending on the application.        Unified Test Methods for Fatigue of VEM, Moisture        Susceptibility, Hot and Cold Condition

FIG. 13 and FIG. 14 describes the basis for Constant and Pulse LoadSeries (CLS and PLS) methods for testing VEM. Four unified test methodsare disclosed here based on the Load Series methodology in the currentinvention. These test methods cover three different temperature rangesand a moisture state using any Test Loading Device (TLD) as follows:

-   -   1. Hot Condition test conducted at temperatures over 30° C. The        hot condition test determines the VEM behavior when subjected to        a Pulse Loads Series with low level stress and at elevated        temperatures.    -   2. Normal Condition test conducted between 0 and 40° C. The        normal temperature test relates to the fatigue cracking behavior        of VEM when subjected to a Pulse Loads Series at high stress        levels and at normal temperatures. Moisture Condition test is a        variation of normal condition test that is conducted at a single        room temperature (about 25° C.) on moisture conditioned        specimens to determine the effect of moisture on VEM.    -   3. Cold Condition test conducted at temperatures below 0° C. The        cold temperature test determines the cracking resistance of VEM        at cold temperatures.        Test Procedure for Normal Condition Test According to the Eight        Embodiment    -   1. VEM is placed under a Loading Device (TLD) at a normal        temperature condition (between 0 and 40° C.) and a Load Series        (PLS or CLC) with high stress level is applied to the material        until DC reaches the Stable Region (SR) but does not reach the        Unstable Region (UR). The Total Deformation (TD), Span and        Deformation per Cycle at Stable Region (SDC) is the test        parameters. The applied load magnitude should be high enough to        induce a measurable amount of SDC but not too high to reach UR.    -   2. Optionally, the load may be increased to a higher level and        step 1 above repeated on the same VEM sample. This process may        be repeated several times for several load levels and each load        level will produce an SDC.    -   3. The same VEM is set to a higher temperature and the test as        in 1 (and optionally 2) is then repeated on the same VEM which        results in new SDC for the higher temperature.    -   4. The process in 1 to 3 above is repeated until test reaches        Unstable Region where Deformation Acceleration (DA) becomes        positive and DC starts to increase per additional cycle. The TD,        Span and SDC for the PLS before test reached UR is defined as        test parameters.        Test Procedure for Moisture Condition Test According to the        Ninth Embodiment    -   1. VEM is placed under a Test Loading Device (TLD) at a dry        condition and a Loading Series (CLS or PLS) is applied to the        material until test reaches the Stable Region but does not reach        Unstable region (UR). Optionally, the load may be increased to a        higher level and the test repeated on the same VEM. This process        may be repeated several times for several load levels until SDC        reaches a predetermined value. (give example of the value) The        Deformation per Cycle at Stable Region (SDC) is then defined as        the initial SDC. (numerical example of how calculated and used)    -   2. VEM is saturated with moisture to a predetermined level and        another Loading Series is applied on the same specimen at the        highest stress level in item 1 above. Optionally, the specimen        may be frozen for any length of time and subsequently thawed        before or after loading. This process may be repeated several        times.    -   3. The VEM is then dried (moisture is removed from sample) to a        predetermined level and another Loading Series is applied on the        same sample at the same stress level as in item 2 above and the        Final SDC is noted.    -   4. Test parameter is the ratio of Initial SDC to Final SDC which        shows the degree VEM has lost integrity due to moisture. (give        example of ratio)

According to one embodiment of the present invention, the test isconducted as a variation of the normal condition test described before.The PLS in steps 1 and 2 of the second embodiment are performed on thespecimen at a single room temperature until a measurable amount of SDCis reached and the load magnitude is noted. The same VEM specimen issubsequently fully saturated with water under high vacuum and the lastPLS and load level is repeated on saturated specimen. Subsequently, thewater is removed from VEM specimen and it is dried to a predeterminedlevel and the last PLS is repeated again.

Test Procedure for HOT Condition Test According to the Tenth Embodiment

The hot condition test utilizes a loading Series (PLS or CLS) similar tothe Normal Condition described above with the exception that the test isconducted at high temperature (above 30° C.) and lower load (or stress)level according to the type of application. The load level is selectedbased on Pulse Load Cycle (PLC) such that the test reaches the StableRegion (SR) and does not reach the Unstable Region (UR) and the SDC is ameasurable amount (i.e. step 4 of the normal condition is ignored). Thismeans that the Deformation Acceleration (DA) should always be negativeand DC should always be reducing per cycle. (Give numerical examples ofDA and its calculation and use.)

Test Procedure for COLD Condition Test According to the EleventhEmbodiment

-   -   1. VEM is placed under a Test Loading Device (TLD) at a cold        condition (less than 0° C.) and a Load Series (CLS or PLS) with        high stress level is applied to the material until test reaches        the Stable Region (SR) and does not reach the Unstable Region        (UR). The Total Deformation (TD), Span and Deformation per Cycle        at Stable Region (SDC) is then defined as the test parameters.        (give numerical examples for calculating test parameter and how        they are used in the test) The applied load magnitude should be        high enough to induce a measurable amount of SDC but not too        high to reach UR.    -   2. Optionally, the load may subsequently be increased to a        higher level at the same temperature and the CLS be repeated on        the same VEM as in 1 above. This process may be repeated several        times for several load levels and each Load Series will have an        SDC.    -   3. Optionally, the temperature of the same VEM may be set to        another temperature and the test is repeated which results in a        new set of SDC for the new temperature.    -   4. The process in 1 to 3 may be repeated as many times as        needed.

The cold, normal, moisture, and hot condition tests may be utilized forany VEM including powder, polymers, rubber, asphalt binder, asphaltmixture, asphalt mixture residue, plastics, gum, and latex having anyshape or size and using any type of Test Loading Devices (TLD).

I claim:
 1. A method of mounting a viscoelastic material (VEM) on a gapbetween a first plate and a second plate of the parallel plate rheometercomprising: a. preparing an appropriate amount of the VEM to fill thegap of a predetermined thickness and create a bulge; b. placing the VEMon the first plate surface; c. heating the VEM to a first temperatureuntil it melts and substantially covers the entire plate surfacecreating a symmetrical dome-shaped appearance; and d. moving the firstplate and the second plate towards each other to the predetermined gap.2. The method of claim 1, wherein the VEM is one or more of oil, powder,melts, paint, polymer, polymer modified material, rubber, rubberproducts, original asphalt binder, aged asphalt binder, extractedasphalt binder from mixture, and or Asphalt Mixture Residue.
 3. Themethod of claim 1, wherein the parallel plate rheometer is a dynamicshear rheometer (DSR) with the first and second plates having a diameterof 8 mm, and wherein the VEM is either an asphalt binder or an AsphaltMixture Residue, wherein, if the VEM is the asphalt binder, the gapbetween the first and second plates is 0.5 mm, and wherein, if the VEMis the Asphalt Mixture Residue, the gap between the first and secondplates is 1.0 mm.
 4. The method of claim 1, wherein the parallel platerheometer is a dynamic shear rheometer (DSR) with the first and secondplates having a diameter of 25 mm, wherein the VEM is an asphalt binder,and wherein the gap between the first and second plates is 1.0 mm. 5.The method of claim 1, further comprising: reducing the temperature to asecond temperature suitable for adhesion of the VEM to the second plate;and allowing sufficient time for the VEM to adhere to the second plate.